The present invention relates to method and apparatus for controlling an optical disc device, and more particularly, but not by way of limitation, to method and apparatus for controlling high-speed rotation of optical disc that can calculate the amount of disc vibration with a goal of increasing the disc rotation speed for maximizing the data transfer rate based on the amount of disc vibration.
In conventional schemes for controlling the rotation speed of an optical disc, the initial rotation speed of the optical disc is set to a predetermined value Wo without regard to the amount of disc vibration. The initial rotation speed Wo is less than the allowable maximum rotation speed Wmax, so that reliable playback of the optical disc is guaranteed against axial and radial vibration of the optical disc.
In some optical discs like CD-ROM titles, the amount of data recorded on an optical disc is normally not enough to fill the optical disc and so data are recorded only in the inner peripheries of the optical disc. When an optical disc rotates at a constant angular velocity (CAV), the linear velocity of tracks increases from inner peripheries to outer peripheries. In an optical disc having only small amount of recorded data, therefore, the linear velocity of tracks having data recorded thereon is always less than the allowable maximum linear velocity VMAX. Accordingly, if an optical disc contains only small amount of data, conventional control schemes cannot provide high data transfer rates.
It is an object of the present invention to provide method and apparatus for controlling high-speed rotation of an optical disc, capable of estimating the amount of disc vibrations and maximizing the data transfer rate by increasing the disc rotation speed based on the calculated amount of disc vibration.
An apparatus for controlling high-speed rotation of optical disc according to the present invention comprises: a means for retrieving data recorded on the optical disc; a means for checking whether the period of sync signals detected from the retrieved data falls within a predetermined interval; a means for measuring the time that elapses after the optical disc begins to rotate; and a means for adjusting the rotation speed of the optical disc based upon the measured time if the period of sync signals falls within the predetermined interval.
In a method for controlling high-speed rotation of an optical disc according to the present invention, the time that elapses until a predetermined signal is detected from the optical disc is measured, the amount of disc vibration is calculated based on the elapsed time, and the rotation speed of the optical disc is adjusted based upon the calculated amount of disc vibration. In another method for controlling high-speed rotation of an optical disc according to the present invention, the number of track traverse signals is counted after the rotation speed of the optical disc exceeds a threshold value and the elapse time is measured, the amount of disc vibration is calculated based on the number of detected track traverse signals or the elapse time, and the rotation speed of the optical disc is adjusted based upon the calculated amount of disc vibration.
In the method and apparatus according to the present invention, if an optical disc is loaded and driven to rotate at a constant angular velocity, the retrieving means retrieves recorded signals from the optical disc, the time measuring means measures the time that elapses after the optical disc begins to rotate, and the checking means checks whether the period of sync signals detected from the data being retrieved falls within a predetermined interval. If the period of sync signals belongs to the predetermined interval, the adjusting means calculates the amount of disc vibration based on the elapse time and adjusts the rotation speed of the optical disc based on the calculated amount of disc vibration.